Shorting device



Dec. 22, 1942. N. N. @KUN 2,30%632 SHORTING DEVICE Filed July l, 1940 INVENTOR BY a ` ATTORNEY Patented Dec. 22, 1942 SHORTING DEVICE Nathaniel N. Okun, Bronx, N. Y., assignor of onethird to CharlesM. Palmer, Washington, D. C.

Application July 1, 1940, Serial No. 343,496

7 Claims.

The invention is concerned with short circuiting means for repulsion induction electric motors and specifically is directed to a short circuiting device comprising an annular band of pivoted and radially disposed electrically conducting members or slugs normally held out of contact with the bars of the commutator of the motor during starting thereof to allow the motor to start on repulsion and after a certain predeter mined speed is reached the outer portions of the swingable members are` swung by centrifugal force to short or engage the commutator bars to permit the motor to operate inductively, this application being a continuation-in-part of my previous application Serial No. 133,556, filed March 29, 1937, now materialized into Patent No. 2,206,045. rThe objects, advantages, the improved and salient functional and structural features of the invention will be more readily understood from the teachings of the following description considered in the light of the accompanying drawing wherein:

Fig. 1 is a sectional view of the shorting device according to the invention illustrating the pivoted slugs thereof normally held out of contact with the commutator bars lby a spiral spring.

Fig. 2 is a sectional View on the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary view of Fig. 1 showing the swingable slugs held in contact with the commutator bars due to centrifugal force and against the resistance of the spiral spring.

Fig. 4 is a modified and fragmentary View of Fig. 1.

Fig. 5 is a view similar to Fig. 1 but illustrating modified spring means for normally holding the slugs out of contact with the commutator.

Fig. 6 is a fragmentary view taken on the line 6--6 of Fig. 5, and

Fig. 7 is a view similar to Fig. 6 but illustrating a modification.

According to Figs. 1-3 inclusive lthe short circuiting device comprises the insulating cup shaped annular shell or casing I3 having a marginal but annular hollow bead defining an inner annular but enlarged channel or groove 36 in which enlarged heads 31 of the annular band of electrically conducting slugs 2| are swngably disposed. These slugs are provided with intermediate attenuated portions 38 terminating in hollow eyes 39 pivotally mounted on the fulcrum ring 4l) disposed in the inner annular channel or groove 4I of the bushing or hub 42 of the insulating shell I3.

The intermediate attenuated portions 38 of each of the slugs 2l are each provided with a recessed or concentric groove 44 adapted to cooperate with Athe annular inwardly overhanging stop rib 45 to limit displacement of heads 31 of the slugs when the motor is moving to a stopping position at which time lips 46 of the slugs retract or move away from the commutator bars I2 by reason of the outward thrust applied to the annular electrically conducting channeled copper shoe 41 which is continuously urged against hat faces 48 of the intermediate attenuated portions 38 of the slugs 2 I by the spiral or tapered spring 49 having its outer and largest convolution -50 disposed and retained in an annular f? channel of the conducting shoe 41r while the inner contracted convolution 5I abuts the inner contracted end 52 of the tapered recess or Ycavity 53 in commutator support II. The contracted end of spring 49 also abuts the motor shaft Ii) and thus is firmly held in place.

With the motor at rest or moving to a stop position the floating copper annular shoe 41 holds the slugs out of contact with the commutator bars I2. In starting from a stop position and after a predetermined speed of the motor shaft has 'been reached, the centrifugal force imparted to the slugs overcomes the resistance offered by the helicoidal spring 49 and hence lips 46 contact or short the commutator bars until such time that thek speed falls below the predetermined speed. Furthermore since the heads of the slugs have considerable mass, the momentum thereof rapidly increases or decreases depending upon the variations in speed and it follows that the slugs are readily responsive and therefore are positive and rapid in operation, that is, engage or disengage the commutator bars when required and promptly.

In the form according to Fig. 4 the annular groove 4I Ain which the tail portions or eyes 39 are pivotally or rotatably mounted is also characterized by the annular insulating beaded ring secured to the hub of the shell by rivets 6I. By the present arrangement the annular band of swingable slugs during assembly may be mounted in the shell I3 in the advance of positioning the beaded ring on the annular hub 42. In other aspects the form according to Fig. 4 is along the lines illustrated in Figs. 1-3.

With the form according to Figs. 5 and 6 an annular sheet metal spring spider has its radially extending and crimped but arcuate fingers 66 engaging the floating annular shoe 41 thus resiliently holding slugs 2| normally away from the commutator bars. Spider 65 however has its lower hub portion xedly retained on the motor shaft I and against the commutator support Il by the annular spacer 68 positioned against the beaded ring 69 having its annular bushing l0 iixedly held on hub 42 and the bushing 'l0 closely lits shaft l0 and is retained against spacer 68 by the snap ring '13, the bead portion 'li of the ring 69 characterizes means to rotatably retain the enlarged rounded portions of the slugs 2l in the annular channel 4|. By this arrangement the fulcrum ring 40 shown in Figs. 1 4' have been eliminated and the enlarged tail portions need not be perforated. In other aspects the embodiment shown in Figs. 5 and 6 is along the lilies illustrated in Figs. 1-3.

In Fig. v, sneu 3e is of metai and is spaced from bushing 14 firmly retained on the reduced porconfined in the annular channel 4| of bead or ,d

bearing 13 by the semi-spherical metal hollow ring 11 having its inner end 18 soldered at 19 to the bushing '14. In other respects the form illustrated in Fig. 7 follows the embodiment shown in Figs. 5 and 6 or in Figs. 1-4 wherein the snap ring holds the insulating shell to position the end of its bead 35 in seal tight relation against the commutator. Thus in all of the forms disclosed a floating copper ring or shoe 4l' is acted upon by spring means to hold the slugs 2l away from the commutator until a predetermined speed is reached and until the centrifugal force overcomes the resistance of the arcuate spring fingers 66 of the relatively thin spider 65 (Figs. 5-7) or overcomes the resistance of helical spring 5l (Figs. l-4). At or above the predetermined speed, lips 46 which have a width coextensive with the width of the substantially disc shaped or bulbous heads 3T, short the bars l2 until the speed drops below the predetermined speed at which time and until stopping of the motor the slugs are urged to their normal and fully retracted position by the spring means.

Various changes may be made in details of construction and arrangement of parts without s.

departing from the spirit of the invention or sacrificing any of the advantages thereof inherent therein.

I claim:

l. In a short circuiting device for a motor comi mutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including a groove and having a hub portion including, an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, and attenuated portions interconnecting said heads and tail portions, the attenuated portion of each of said slugs having a substantially rectilinear face and a notch; an annular shoe positioned against said faces, and spring means for holding said shoe yieldingly against said rectilinear faces whereby the Walls of said notches abut said rib to limit displacement of said heads away from said cornmutator.

2. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including an annular groove and a hub portion having an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, and attenuated portions interconnecting said heads and tail portions, the attenuated portion of each of said slugs having a substantially rectilinear face and a notch; an annular shoe positioned against said faces, and a member having resilient fingers for holding said shoe yieldingly against said rectilinear faces whereby the Walls of said notches abut said rib to limit displacement of said heads away from said commutator.

3. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including an annular groove and a hub portion having an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, and attenuated portions interconnecting said heads and tail portions, the attenuated portion of each of said slugs having a substantially rectilinear face and a notch; an annular shoe positioned against said faces, and helicoidal spring means for holding said shoe yieldingly against said rectilinear faces whereby the walls of said notches abut said rib to limit displacement of` said heads from said commutator.

4. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including an annular groove and a hub portion having an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large and substantially disc shaped heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, and attenuated portions interconnecting said heads and tail portions, theattenuated portion of each of said slugs having a substantially rectilinear face and a notch; an annular shoe positioned against said faces, and spring means for holding said shoe yieldingly against said faces whereby the Walls of said notches abut said rib to limit displacement of said heads awayfrom said commutator. v

5. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaftV of said motor and having a beaded portion including an annular groove and ahub portion having an annular channel, an annular rib extending from said body intermediate Vsaid groove and channel; a plurality of slugs each having a relatively large head disposed in said groove, lips extending from said heads, substantially disc shaped tail portions rotatably retained in said channel, and attenuated portions interconnecting said heads and tail portions, the attentuated portion of each of said slugs having a substantially rectilinear face and a notch; an annular shoe positioned against said faces, and spring means for holding said shoe yieldingly against said faces whereby the walls of said notches abut said rib to limit displacement of said headsaway from said commutator to dispose said lips out of contact with the latter below a predetermined speed of said shaft.

6. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including an annular groove and a hub portion having an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, an attenuated portion interconnecting said heads and tail portions, the attenuated portion of each of said slugs having a substantially rectilinear face and a notch, a ring positioned against said faces, and a member having a plurality of radially arranged and spaced resilient ngers for holding said ring yieldingly against said rectilinear faces whereby the Walls of said notches abut said rib to limit displacement of said heads away from said commutator.

7. In a short circuiting device for a motor commutator, an annular shell adapted to be mounted on the shaft of said motor and having a beaded portion including an annular groove and a hub portion having an annular channel, an annular rib extending from said body intermediate said groove and channel; a plurality of slugs each having relatively large heads disposed in said groove, substantially disc shaped tail portions rotatably retained in said channel, an attenuated portion interconnecting said heads and tail portions, the attenuated portion of each of said slugs having a substantially rectilinear face and a notch, any electrically conducting ring positioned against said faces, and a relatively thin spider having a plurality of arcuate and spaced resilient ngers for holding said shoe yieldingly against said rectilinear faces whereby the Walls of said notches abut said rib to limit displacement 20 of said heads away from said commutator.

NATHANIEL N. OKUN. 

